Medical fluid injection devices are typically used to inject medical fluid into a patient. These devices often include one or more reservoirs to hold the medical fluid, and one or more pressurizing units to inject the medical fluid into the patient. For example, a contrast media powered injection device may include a reservoir containing contrast media and a syringe that is used to inject the contrast media into the patient. The contrast media injection device may be used during certain medical procedures, such as an angiographic or a computed tomography (CT) procedure.
Many medical fluid injection devices include one or more syringes to inject fluid. A syringe has a chamber for holding the fluid and a plunger that is moveable within the chamber. The fluid is typically drawn into the chamber from a fluid reservoir when the plunger is moved in a first direction. The fluid is then expelled from the chamber and into the patient, via a catheter, when the plunger is moved in a second, opposite direction. The fluid is delivered at a rate that may be determined by a speed of movement of the plunger.
In many cases, high-pressure tubing (such as high-pressure braided tubing) is used to deliver medical fluid to a syringe from a fluid reservoir, or from the syringe to a patient line. An injection device that has been loaded with a syringe may need to control the flow of fluid through high-pressure tubing into and/or out of the syringe. For example, the injection device may control one or more pinch valve mechanisms to controllably open or seal off the high-pressure tubing, thereby controlling the flow of fluid through the tubing. Typically, higher forces are needed to pinch, and seal off, high-pressure tubing as compared with lower-pressure, or non-braided, soft tubing.